In recent years, electronic location devices, especially global positioning systems (GPSs), have become quite commonplace, and have been proven both useful and popular in many different applications or uses. Due to their ever-increasing deployment, most automobile drivers and passengers are now familiar with some type of navigation device that includes some type of positioning system. A navigation device is typically embodied as an integrated unit that provides up-to-the-minute routing information relative to the device's current position, including which roads to follow, where and when to turn, which lanes must be used, and the like.
FIG. 1 is a pictorial diagram illustrating an exemplary, integrated navigation device 100, such as those commonly found in the prior art. The exemplary navigation device 100 includes a display subsystem 102, which, in this example, is illustrating a map of the immediate surroundings of the navigation device, as well as route information for a user. As is typical with many navigation devices, an icon 104 illustrates the current location of the navigation device 100 (and presumably the vehicle in which it is located), as well as a defined route 106 a driver is to follow to arrive at a specified destination 108.
As those skilled in the art will appreciate, an exemplary navigation device 100 also frequently includes a number of user inputs, such as control buttons 110, and/or a keypad 112 that includes alpha-numeric keys for text and/or data entry. Of course, those skilled in the art will appreciate that navigation devices come in a variety of configurations with numerous options. The present illustration is meant only as an example, and should not be construed as limiting upon the present invention.
While most location devices, such as a GPS or wireless telephone, could be designed to be very accurate in determining the location of the device, current location devices are known to include some degree of inaccuracy. For example, most GPS owners know that their device will report a geographic position (in terms of latitude and longitude) for the device that is only accurate within some tolerance. In fact, for most GPS systems, the reported position is accurate within a radius of 10 to 100 meters of the actual position. While in many cases this inaccuracy is unimportant, when the location device is part of a navigation system, and the reported position is 10 meters “off” the actual position, this may cause the navigation system to illustrate a corresponding vehicle's position as traveling down the middle of a busy office lobby, rather than on a street in front of the building.
FIG. 2 is a pictorial diagram illustrating an exemplary map 200 displayed by a navigation system, such as navigation device 100 of FIG. 1, and further illustrating the problems associated with the inaccuracies of location devices. In particular, the navigation system, in the course of providing up-to-date navigation information to the driver of an automobile, will typically periodically obtain the current position from its location subsystem (such as a GPS unit). Furthermore, in addition to the inaccuracies of the location subsystem, due to the inaccuracies of the navigation system's data, the exact location 202 will fall somewhere off of an established road. For instance, assume that reported location 202 is the most recent position obtained by an integrated navigation device. As can be seen, location 202 does not correspond to any established road. Instead, there are five different road segments, including road segments 204, 206, 208, 210, and 212, that may fall within the understood margin of error. Clearly, this presents a problem for the navigation system, which may ultimately report to the user that the vehicle is traveling down a road, or through a building, that it is not.
Of course, the map, or route data, that the navigation system uses may also be in error. However, no matter what the error, it is very disconcerting for the navigation system to report that the driver is navigating the vehicle through a lake, down the wrong way of a one-way street, or in the middle of an office building, when in fact, it is not true. Accordingly, what is needed is a navigation system, and a method for implementation on a navigation system, that efficiently resolves discrepancies between a location position as reported by a location service, and the route data relied upon by the navigation system. The present invention addresses this and other issues found in the prior art.